N/V/D/C/IBS Flashcards
N/V causes?
GI irritation, motion sickness, vestibular dz, hormone imbalance, drugs and radiation, exogenous toxins, pain, psychogenic factors, intracranial pathology
N/V clinical presentation?
everyone aware of. dehydration can occur: inc. thirst and dry mouth, less frequent urination, tachycardia, pinching skin takes longer to go down (dec. turgor)
What is the N/V non-pharm tx?
rehydrate (ORS = oral rehydration solutations), avoid dairy, BRAT diet 24 hrs. after fluid only (banana, rice, apple sauce, toast dry)
What are the types of N/V Pharmacologic tx?
- 5-HT3 Antagonists
- Dopamine Antagonists
- Antihistamines
- Cannabinoids
What are the 5-HT3 Antagonists and how do they work?
Ondansetron (Zofran) used Granisetron (Kytril) Dolasetron (Anezmet) MOA: antagonism of the 5-HT4 receptor in the chemo-receptor trigger zone (CTZ) Route: PO, PR, IM, IV
What are the 5-HT3 Antagonists indications and ADRs?
Indications: tx and prevention of postoperative N/V, chemo-induced N/V
ADRs: HA (common), dizziness, diarrhea, abdo pain
What are the Dopamine Antagonist and how do they work?
Metoclopramide (Reglan)
Trimethobenzamide (Tigan)
Phenothiazine (Prochlorperazine - Compazine)
MOA: antagonist of D2 receptors in CTZ, at higher doses metoclopramide also block 5-HT3 receptors. Also promotes gastric emptying and small intestine peristalsis = prokinetic effects!!!
What are the Dopamine Antagonists CIs and ADRs?
CI: GI - hemorrhage, obstruction or perf (d/t prokinetic effects), caution in pts w/depression, pheochromocytoma, seizure, caution in kids
ADRs: extrapyramidal effects (d/t blocking DA - parkinson-like effects), restlessness, anxiety, drowsiness, fatigue, hallucinations, CV: HTN, HPOTN, AV block, bradycardia, agranulocytosis
Name the types of Antihistamines and how they work?
Promethazine (Phenergan), Phenothiazine
MOA: blocks H1 –> effectiveness appears to be w/motions sickness and vestibulocochlear dz, antagonist of D2 receptors in the CTZ.
Dose: 12.5-25 mg Q4hr. PRN, IV, PO, PR (MUST be diluted with NS for injection, dangerous in extravasation)
What are the ADRs and cautions for Antihistamines
ADRs: dry mouth, dizziness, Parkinsonian symptoms (dyskinesia, dystonias, akathisia, neuroleptic malignancy syndrome (life threatening), blood dyscrasias. Caution in BPH, urinary retention, glaucoma
Cannabinoids can be used to treat N/V and what is it called/side effects, etc?
Dronabinol (Marinol), MOA not well defined.
Side effects: drowsiness, sedation, inc. appetite
What is normal motility of the intestines called and what does it do?
peristalsis, acts to mix bowel contents thorougly, to propel them in the caudal direciton
Regulation of normal intestinal motility is under control of what?
neuronal and hormonal
What classes of drugs are used to affect GI motility
laxatives, antidiarrheal agents, prokinetic agents, antiemetic agents, antispasmodics
What is the definition of constipation
2 or more of: straining >25% of time, lumpy/hard stools >25% of time, feeling of incomplete evacuation >25% of time, 2 or fewer BM in 1 week
What are some causes of conatipaiton?
Metabolic: hypothyroid, hypercalcemia, hypokalemia
GI disorder: tumors, IBS, diverticulitis
Pregnancy
Neurogenic: trauma to brain/spinal cord, CNS tumor, Parkinson’s
What are some meds that cause constipation
Opiates (most), Ca and Al antacids, Fe, Ca++ channel blockers (Verapamil), Clonidine, Anticholinergics (antihistamines, antiparkinsonians, TCA)
What are some non-pharm tx/management/prevention of constipation
drink plenty of H20/fluids, “P” jucies, adequate exercise, high fiber diet including: insoluble - shorten intestinal transit time and inc. stool bulk (whole grains/bran); water soluble fiber: more moist stool and less effect on transit time (fresh fruits/veggies)
What are laxatives used for?
hasten transit time in the gut and encourage defecation. Also used to clear bowel prior to medical and surgical procedures
What are the laxatives from lecture?
bulk-forming laxatives emollients and lubricants saline cathartics osmotic laxatives stimulant laxatives
What are the bulk forming laxatives?
Psyllium (Metamucil)
Methylcellulose (Citrucel)
Polycarbophil (Fibercon)
What is the MOA of bulk-forming laxatives and their onse?
inc. volume of non-absorbable solid residue w/water, distending colon and stimulating peristaltic activity, inc. rate of colonic transit . adequate fluid intake is important while taking these. onset: 2-3 days?
For which type of patients are bulk-forming laxatives considered first line? What are some CIs?
bedridden or geriatric w/chronic constipation. also good in pregnancy
CI: pts w/stenosis, ulceration or adhesions, fecal obstruction
What are the ADRs and DIs for bulk-forming laxatives?
ADRs: flatulence, abdo distention, gastro obstruction
DI: binds to drugs and reduces absorption - separate from other meds
What are some other uses of bulk-forming laxatives
ability of these agents to absorb H20 makes them useful for relieving sxs of mild diarrhea, several months use can relieve sxs of irritable bowel syndrome, lowering cholesterol.
What is the emollient from lecture and what is the indication?
Docusate sodium (Colace). Indication: to avoid straining, after MI, surgery, opiates FIRST LINE pregnant women (also bulk-forming laxatives)
What is the MOA, onset and CIs for emollients (Docusate sodium - Colace?)
onset 1-3 days
MOA: surfactant brings H20 into stool, facilitates mixing of aqueous and fatty materials within intestines, increase H20 and electrolyte secretion in small/large bowel.
CI: fecal impaction, s/sx of appendicitis
Mineral oil is what? and used for?
a lubricant - chronic use is discouraged!, mainly used to avoid straining, after Mi, rectal surgery
What is the onset time, MOA and caution, for lubricants (mineral oil)?
6hr-3 days (PO or PR)
MOA: coats stool (allows easier passage), inhibits colonic absorption of H20
caution: avoid in elderly, aspiration risk and dec. absorption of fat-soluble vitatmins (DEAK) - may leak from anal sphincer.
What are the osmotic agents?
Lactulose and Sorbitol
What is the MOA and indication for Lactulose (osmotic agent)?
MOA: disaccharide that is metabolized by bacteria in colon to low-molecular weight acids = osmotic effect (so pulling in fluid). NOT considered 1st line agent. May result in flatulent, cramps. electrolye imbalances. More commonly used in pts w/hepatic encephalopathy. PO softens stools in 1-3 days
What is MOA for Sorbitol (osmotic agent)
MOA: monosaccharide creates osmotic gradient when used as a 70% solution, hyperglycemia. PO dose softens stool in 1-3 days
What are the types of saline cathartics?
Magnesium hydroxide (MOM), Magnesium sulfate (epsom salts), sodium phosphate (Fleets enema), Magnesium citrate (citrate of Magnesia)
What is the MOA/CI/onset for saline cathartics?
onset: 30min-6hr. PO, 5-30min. PR (enema)
MOA: Mg++ or Na+ salts are poorly absorbed; they inc. the H20 content of the bowel through osmosis.
CI: impaired renal fxn. Mg and Na accumulation, CHF, no sodium for HTN pts
What is the MOA for Castor Oil?
MOA: metabolized to ricinoleic acid - stimulates secretory pathways.
Decreased glucose absorption, promotes intestinal motility. NOT for routine use.
What is the MOA/onset for glycerin suppository?
MOA: osmotic action in rectum
onset:
What are the two types of Glycerin/Hyperosmotic agents?
Polyethylene glycol (Miralax) and Polyethylene glycol (PED, GoLYTELY)
How do you use Miralax (Polyethylene glycol)
17g mixed w/water or juice, usually 2 weeks duration, chronic use OK!!
onset: 1-3 days (Miralax)
MOA: osmotic
Note: relatively safe, OK in kids!
What is the other use for the Polyethylene glycol (PED, GoLYTELY)? and how is it used/onset etc.?
used for colonic cleansing before diagnostic procedures.
onset: 1 hr. after initiation
MOA: osmotic agent that causes retention of H20 resulting in softer stool and more frequent defecation.
Note: 4 L over 3 hrs (8 oz glass q10min) NOT for chronic use!! Avoid in patients with intestinal obstruction!!!
What are the stimulant laxatives
Diphenylmethane Derivations - Bisacodyl (Dulcolax)
Anthraquinone Laxatives - Senna (Senokot)
What is the MOA of Bisacodyl (Dulcola) (it’s a diphenylmethane derivative, stimulant laxative)
stimulate nerve plexus of colon (>12 yr oral: 5-30mg Qday; rectally: Qday) onset: 6-8 hr (PO); 1-6 (PR). DON’T take w/in 1 hour of antacids, milk or milk products
What are the ADRs and long term effects of Bisacodyl (Dulcolax)?
ADRs: intestinal cramps, can cause fluid and electrolyte imbalance, PINK colored urine and feces
Long term use: could cause damage to nerve plexi, resulting in deterioration of intestinal function –> atonic colon!
What is the MOA for the Anthraquinone Laxative Senna (Senokot)? (it’s a stimulant laxative)
MOA: increased peristalsis. Co-formulated w/docusate (Senokot-S)
>12 yrs: 1-4 tabs Qday - NOT rec
What are teh ADRs, long term effects and CI of Senna (Senokot) an anthraquinone laxative (stimulant laxative type)
ADRs: yellow-brown to red colored urine, large doses can produce nephritis
Long-term use: could damage the nerve plexi, leading to deterioration of intestinal function, atonic colon
CI: PREGNANCY and acute intestinal inflammation!!!
What is the MOA and side effects/CI of Lubiprostone (Amitiza)
MOA: chloride-channel activator, works by inc. fluid secretion locally in the small intestine by activating the ClC-2 chloride channel Side effects: N/D onset: 1d-1 week+ CI: intestinal obstruction, pregnancy USED for opiate-induced C.
What is the MOA of Methylnaltreoxone?
MOA: peripherally acting antagonist of mu. Does not cross BBB, reduces effects of opiods of periphery, NOT centrally.
Renal dose adjustmend for CrCl